This invention relates to a drill grinder, and, more particularly, to a portable drill grinder useful for sharpening a drill point.
Portable drill grinders useful in machine shops and the like have been available for decades. One of the original basic disclosures relating to such grinders is found in U.S. Pat. No. 2,109,308 for a drill grinder issued Feb. 22, 1938, incorporated herewith by reference. A companion patent disclosing a portable drill grinder and setting forth information regarding the technology of grinding drill points on drill bits is U.S. Pat. No. 2,124,093 for a grinding machine issued Jul. 19, 1938. Subsequent patents relating to drill grinder constructions include U.S. Pat. No. 4,001,975 and U.S. Pat. No. 4,093,247. Other patents relating to this general technology include U.S. Pat. No. 4,485,596 and U.S. Pat. No. 4,471,581.
Typically, drill grinders of this type include a grinding wheel, which is mounted on a platform. A collet or chuck is provided to receive and hold a drill bit. A bracket is provided to support the collet in opposition to the grinding wheel. The collet is manipulated in the bracket to engage the point of the drill bit against the grinding wheel and thereby grind or sharpen the drill bit in accord with the manner in which the collet is manipulated within the bracket. Collet manipulation is controlled by compatible cams and followers on the collet and bracket. Nonetheless, adjustment of the collet and manipulation of the drill bit within the collet to effect proper forming of the point of the drill have long been challenging problems.
The present invention relates to a drill grinder which addresses the manner in which the bracket that supports the collet or chuck may be moved with respect to the grinding wheel to effectively grind the drill point. The invention also is directed to the collet construction as well as mechanisms for properly aligning a drill bit within a collet in order to enhance the point forming operation, including split point forming and thin web formation on a drill point.